I find it odd that people criticize the Harfoots for not sounding authentically Irish, when of course they are not intended to be Irish. The story takes place in a mythic age of the world where there isn't any Ireland as yet, when there won't be any Irish for thousands and thousands of years yet, and if there were, the Harfoots wouldn't be them in any case. So they do have a kind of sort of Irish-like lilt. They need something to set them apart from the big folk.
(And anyone who hates the accents here, they must have despised Jackson's The Lord of the Rings, where a number of the actors slipped in and out of their accents throughout the movie. Especially, I blush to admit, a couple of the Americans.)
And the dwarves in RoP, supposedly stereotypically Scottish ... but in what ways do they appear Scottish, stereotypically or otherwise (aside from Durin IV's red hair and beard—but the Scots are not the only people where red or reddish hair is relatively common). They don't dress as stereotypical Scots, their architecture and lifestyle under the ground are not Scottish. Their language, I believe is more closely related to Hebrew than to any Celtic language—it looks more Hebrew, anyway. Their music doesn't sound like Scottish music. Are their accents Scottish? I thought they sounded Welsh, but maybe that's because Owain Arthur (Durin IV) has such a strong Welsh accent in the interviews that I super-impose it on his performance.
Look, if people don't like the show, that's fine. We all like what we like and dislike what we dislike. No reasons are necessary. . We are allowed to feel what we feel. But if a reason is given, it would help if it was easier for me to comprehend.